In recent years, there is an increasing demand from consumers toward dyeing their hair in a lighter color than their own haircolor (starting haircolor), and many products generally called “fashion hair dyes” are available on the market.
Hair dyes, which are used for such purposes and include hair bleaches, are each composed of a first pack containing an alkali agent and a second pack containing an oxidizing agent. The alkali agent employed in the first pack has been added to heighten bleaching or dyeing effect and to obtain a wide range of colors ranging from a light color to a deep color. In particular, when one wants to change his or her hair into a tone lighter than the tone of his or her own haircolor, sufficient bleaching power is required. When a hair dye is used for such purposes, a fully sufficient amount of an alkali is therefore required. To dye hair well with good color retention, a sufficient amount of an alkali is also required.
Conventionally, ammonia has been used as an alkali agent in general. Ammonia is, however, accompanied by drawbacks that it has an intensely irritating odor and makes consumers feel unpleasant upon dyeing.
Transition metals have, therefore, been used in attempts to accelerate a reaction with an oxidizing agent and hence to heighten bleaching power or dyeing power (for example, JP 4-312514 A, JP5-124940A, JP6-87727A, and JP4-312514). These attempts, however, all require further treatment with a hair dye after hair is left over with a metal-ion-containing preparation applied thereon beforehand. They thus involves a problem of irksomeness, and moreover, they neither have sufficient dyeing ability nor assure satisfactory color retention.
It has also been attempted to incorporate transition metal ions in first packs (for example, JP 61-130209 A and JP 6-65643 B). However, such first packs are all used under neutral to weak alkaline conditions of pH 6 to pH 8.5, and accordingly, their alkali contents are not sufficient. No sufficient bleaching power is thus available from them, leading to failure in dyeing hair in a light color. These attempts also involve a problem that a dyed color does not stay long.
An object of the present invention is to provide a hair dye composition, which does not give off an intensely irritating odor and has low irritating property, can change hair into a lighter tone in a short time or can dye hair well in a color ranging from a light color to a deep color, and moreover, assures good retention of the thus-obtained tone or color.